The logical structure of a typical relational database is determined by its dictionary objects. These objects can be of a number of object types, e.g., tablespaces, users, tables, views, sequences, stored procedures, etc.
The Oracle Metadata API, introduced in Oracle 9i, provides a central facility for extracting metadata for one or more objects of a specific object type. The 9i implementation uses an OPEN-FETCH-CLOSE programming model: the user issues an OPEN for a particular object type and then repeatedly FETCHes objects of that type; upon completion, the user CLOSEs the object type context. A user can specify one or more filters that restrict the set of objects to be fetched. The Oracle 9i implementation provides a powerful and flexible mechanism for fetching objects within a particular object type.
This API is described in U.S. application Ser. No. 09/672,914, filed on Sep. 28, 2000, “Aggregating and manipulating dictionary metadata in a database system,” the entire teachings of which are incorporated by reference herein in their entirety.